Abstract
In late summer, Northern grass frogs, Rana pipiens, intraspinally administered dynorphin produces a potent, dose-dependent antinociceptive action as measured by the acetic acid test used to evoke a hindlimb wiping response. Surprisingly, in fall, frogs which have entered hibernation, intraspinal dynorphin produces no antinociception action. Intraspinal morphine shows a decreased effect in fall frogs while systemic morphine is equi-effective in summer and fall frogs. Immobilization stress, previously shown to be mediated by endogenous opioid systems in this amphibian, produces a robust increase in nociceptive thresholds in summer frogs while the nociceptive thresholds of fall frogs are unaffected by this procedure. Summer frogs adapted to cold room (4 °C) show a significant decrease in nociceptive thresholds, compared to cohorts kept at room temperature, and cold-adapted frogs returned to room temperature show a naloxone-attenuated increase in nociceptive threshold. Collectively, these data suggest that endogenous opioid systems in these northern frogs are down-regulated during fall hibernation.
| Original language | English |
|---|---|
| Pages (from-to) | 227-231 |
| Number of pages | 5 |
| Journal | Brain Research |
| Volume | 494 |
| Issue number | 2 |
| DOIs | |
| State | Published - 14 Aug 1989 |
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Keywords
- Antinociception
- Dynorphin
- Hibernation
- Intraspinal
- Morphine
- Opioid
- Rana pipiens
- Stress
Cite this
}
Endogenous opioid system down-regulation during hibernation in amphibians. / Stevens, Craig; Pezalla, Paul D.
In: Brain Research, Vol. 494, No. 2, 14.08.1989, p. 227-231.Research output: Contribution to journal › Article
TY - JOUR
T1 - Endogenous opioid system down-regulation during hibernation in amphibians
AU - Stevens, Craig
AU - Pezalla, Paul D.
PY - 1989/8/14
Y1 - 1989/8/14
N2 - In late summer, Northern grass frogs, Rana pipiens, intraspinally administered dynorphin produces a potent, dose-dependent antinociceptive action as measured by the acetic acid test used to evoke a hindlimb wiping response. Surprisingly, in fall, frogs which have entered hibernation, intraspinal dynorphin produces no antinociception action. Intraspinal morphine shows a decreased effect in fall frogs while systemic morphine is equi-effective in summer and fall frogs. Immobilization stress, previously shown to be mediated by endogenous opioid systems in this amphibian, produces a robust increase in nociceptive thresholds in summer frogs while the nociceptive thresholds of fall frogs are unaffected by this procedure. Summer frogs adapted to cold room (4 °C) show a significant decrease in nociceptive thresholds, compared to cohorts kept at room temperature, and cold-adapted frogs returned to room temperature show a naloxone-attenuated increase in nociceptive threshold. Collectively, these data suggest that endogenous opioid systems in these northern frogs are down-regulated during fall hibernation.
AB - In late summer, Northern grass frogs, Rana pipiens, intraspinally administered dynorphin produces a potent, dose-dependent antinociceptive action as measured by the acetic acid test used to evoke a hindlimb wiping response. Surprisingly, in fall, frogs which have entered hibernation, intraspinal dynorphin produces no antinociception action. Intraspinal morphine shows a decreased effect in fall frogs while systemic morphine is equi-effective in summer and fall frogs. Immobilization stress, previously shown to be mediated by endogenous opioid systems in this amphibian, produces a robust increase in nociceptive thresholds in summer frogs while the nociceptive thresholds of fall frogs are unaffected by this procedure. Summer frogs adapted to cold room (4 °C) show a significant decrease in nociceptive thresholds, compared to cohorts kept at room temperature, and cold-adapted frogs returned to room temperature show a naloxone-attenuated increase in nociceptive threshold. Collectively, these data suggest that endogenous opioid systems in these northern frogs are down-regulated during fall hibernation.
KW - Antinociception
KW - Dynorphin
KW - Hibernation
KW - Intraspinal
KW - Morphine
KW - Opioid
KW - Rana pipiens
KW - Stress
UR - http://www.scopus.com/inward/record.url?scp=0024405037&partnerID=8YFLogxK
U2 - 10.1016/0006-8993(89)90590-8
DO - 10.1016/0006-8993(89)90590-8
M3 - Article
C2 - 2570621
AN - SCOPUS:0024405037
VL - 494
SP - 227
EP - 231
JO - Brain Research
JF - Brain Research
SN - 0006-8993
IS - 2
ER -